Part of the official UK Kennel Club testing scheme in Australian Cattle Dog, Bull Terrier, Bull Terrier (Miniature), Chinese Crested, Jack Russell Terrier, Lancashire Heeler, Parson Russell Terrier, Sealyham Terrier, Tibetan Terrier and Welsh Terrier
Primary lens luxation (PLL) is a painful and potentially blinding inherited eye disease that typically affects dogs between 3 and 8 years of age and in many breeds is caused by a single nucleotide substitution in the ADAMTS17 gene.
PLL is the term given to the spontaneous displacement or movement of the lens from its normal position within the eye, as a result of rupture of the lens zonules that hold the lens in its normal position. The zonules are a network of tiny fibres that attach the edge of the lens to the ciliary muscle that circles the eye, in the same way that springs attach a trampoline to its frame. Following zonule rupture the lens usually moves to the anterior chamber at the front to the eye where it can cause damage and rapid onset glaucoma by obstructing the drainage of fluid out of the eye resulting in an increase of pressure within the eye. Glaucoma can cause irreversible vision loss if not treated quickly. PLL is invariably bilateral (occurs in both eyes), although a period of several weeks or months might separate luxation of the two lenses. Clinical signs of PLL include sudden onset of eye pain, clouding of the cornea (the front of the eye will look blue), redness of the “white” of the eye and a reluctance to exercise. PLL should be considered an emergency and veterinary assistance sought immediately.
Lens Luxation can also occur secondary to other primary eye disorders, including primary glaucoma, cataracts, inflammation and trauma.